General

When backing up resources in OpenStack, it's important to understand the difference between two primary methods:

VM Images (Glance): These capture the entire virtual machine, including the operating system, applications, and configuration. VM images are useful for cloning VMs, creating templates, or disaster recovery scenarios. They're managed through the Glance service.
Volume Backups (Cinder): These are point-in-time copies of block storage volumes. Volume backups preserve the data within a volume and can be used to restore the volume to the exact state it was in when backed up. They're ideal for data recovery and are managed through the Cinder service.

Choose the appropriate method based on your recovery needs: volume backups for data recovery, VM images for full system recovery or replication.

Before starting make sure you are in the machine where you configured openstack client and you can run openstack commands as described in EWC - OpenStack Command-Line client

Restoring VMs from Images

OpenStack provide a mechanism to replace the underlying disk of an existing VM with an image without creating a new VM instance running the following command:

openstack server rebuild VM-NAME --image IMAGE_ID

where

```
VM-NAME: The name of the existing VM
```

IMAGE_ID: Name of the backup image of the VM you created before

Restoring Volume Backups

To restore a backup to a new volume, first you need to detach the volume from the VM:
1. ssh into your VM
2. become root
3. unmount the volume
  sudo umount --verbose <path-to-volume>
Then you can restore the backup to the volume with OpenStack (from the machine where you are running Openstack commands):

openstack volume backup restore BACKUP_ID VOLUME_ID

Where:

BACKUP_ID: The ID of the backup to restore
VOLUME_ID: The ID of the volume to restore to (must be at least as large as the original volume)

3. Now, you need to attach the volume again to the VM as explained in `Configuring the extra volume in the instance`.